Electronics > Repair
Tektronix 7613 display and power supply problems
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BlownUpCapacitor:
I recently bought a Tektronix 7613 from a local electronics recycling center, and it doesn't work, as one might just expect.

It appears that the 7B53A sweep module is creating sweep voltages, however, probing the horizontal deflection plates using differential inputs, as in putting channel two to invert and use the add function on my tek 2230, the waveform looks garbage and filled with noise.

The voltage on the 130v supply is low at 119, and the intensity doesn't go up. The trace is very dim. Using my cheap multimeter I read 0.008 volts AC ripple on the +5v line. I will use my HP 427A once I find it to make sure that's true.

Applying a signal to the vertical amplifier produces some odd results with the signal amplitude varying with vertical position. Amplitude is low at the center, amplitude gets higher when the trace is offset.

Measuring the anode voltage with a BK HV probe yields zero volts? I hear high voltage and the CRT is displaying something however my meter reads nothing. Perhaps my meter is broken.

Disconnecting power to the horizontal amp board gives me an unfocused dot at the center of the screen.

I have Sunday and today to convince my mom that spending $80 was not a waste and she doesn't need to kick my ass.

Keep in mind I don't have any formal electronics education but can do basic troubleshooting and read schematics. 4 years self taught from the age of 10.
BlownUpCapacitor:
Using my HP analog meter I read 14 volts AC on the 130v line, 14v AC on +50v, and oh my god everything supply line was greater than 2v AC.

Perhaps just a filter capacitor issue? I doubt it though...
BlownUpCapacitor:
So it was a capacitor problem on the 130v rail. Adding a 1960s 150uF 150v sprauge capacitor in parallel gives me a nearly spot on 130v coming in at 129.2v.

Trace also looks much better but still having focusing problems. This is without inserting a vertical plug in. Inserting a vertical plug in gives me garbage noise.
BlownUpCapacitor:
Garbage on the vertical
p.larner:
check all the psu caps.
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